Torqueable and deflectable medical device shaft

ABSTRACT

A medical device shaft for connection with a handle and for insertion within a body includes an elongated, deflectable shaft having a proximal shaft portion, an intermediate shaft portion, and a distal shaft portion. The elongated, deflectable shaft includes a transition in stiffness from the proximal shaft portion to the distal shaft portion. In a preferred implementation, the shaft includes a plurality of slits that extend perpendicular to a longitudinal axis of the shaft. Varying at least one of the number of slits, the location of slits, the frequency of slits, the orientation of the slits, the size of the slits, and the depth of the slits varies the transition of stiffness.

FIELD OF THE INVENTION

The present invention relates, in general, to deflectable medical deviceshafts, and, in particular, to deflectable catheter shafts.

BACKGROUND OF THE INVENTION

In order to facilitate the advancement of catheters through body lumenssuch as an artery, deflectable catheters have been developed. Thesimultaneous application of torque at the proximal portion of thecatheter and the ability to selectively deflect the distal tip of thecatheter in a desired direction permits the physician to adjust thedirection of advancement of the distal portion of the catheter, as wellas to position the distal portion of the catheter during, for example,delivery of an occlusive implant.

A physician may manipulate the proximal portion of the catheter to guidethe catheter through the vasculature. The deflection of the distal tipis typically provided by one or more steering wires that are attached atthe distal portion of the catheter and extend to a control handle thatcontrols the application of tension on the steering wires. In order tomaneuver around turns and bends in the vasculature, the physicianobserves the catheter fluoroscopically, and selectively deflects the tipand rotates the proximal portion of the catheter shaft.

It is critically important to have sufficient flexibility in the distalportion of the catheter shaft so that when the catheter is advancedthrough a blood vessel, the catheter may follow the inherent curvatureof the vessel without puncturing the vessel wall. However, it is alsoimportant to maintain stiffness in the proximal portion of the cathetershaft to allow the distal portion of the catheter to be manipulated bythe physician. Therefore, there exists a need for a catheter shafthaving a flexible, atraumatic distal portion while maintaining asufficiently stiff proximal portion.

SUMMARY OF THE INVENTION

An aspect of the invention involves a medical device shaft forconnection with a handle and for insertion within a body. The medicaldevice shaft includes an elongated, deflectable shaft having a proximalshaft portion, an intermediate shaft portion, and a distal shaftportion. The elongated, deflectable shaft includes a transition instiffness from the proximal shaft portion to the distal shaft portion.In a preferred implementation, the shaft includes a plurality of slitsthat extend perpendicular to a longitudinal axis of the shaft. Varyingat least one of the number of slits, the location of slits, thefrequency of slits, the orientation of the slits, the size of the slits,and the depth of the slits varies the transition of stiffness.

Other features and advantages of the invention will be evident fromreading the following detailed description, which is intended toillustrate, but not limit, the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of preferred embodimentsof the present invention, in which similar elements are referred to bycommon reference numerals.

FIG. 1 is a side-elevational view of an exemplary catheter having acatheter shaft constructed in accordance with an embodiment of theinvention.

FIG. 2A is a side-elevational view of a catheter shaft constructed inaccordance with an embodiment of the invention with portions of thecatheter shaft cut away.

FIG. 2B is a side-elevational view of a portion of the catheterillustrated in FIG. 2A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, a catheter 10 including a torqueable anddeflectable shaft or body 20 constructed in accordance with anembodiment of the present invention will now be described. The catheter10 will first be generally described before describing the torqueableand deflectable shaft or body 20. The catheter shaft 20 will bedescribed as being used within the vascular system of a patient;however, the catheter shaft 20 may be used within other lumens,passages, ducts, tracts, openings, etc. in the body other than bloodvessels. Further, the shaft 20 may be a torqueable and deflectable shaftor body of a medical device other than a catheter.

The catheter body 20 includes an operative distal tip portion 50. Thecatheter 10 further includes a catheter handle 60 with a steering knob70 to control the distal tip portion 50 of the catheter body 20 whenguiding the distal tip portion 50 through the vascular system of thebody. The steering knob 70 is attached to steering wires that extendthrough an interior lumen of the catheter body 20. The steering wiresterminate and are anchored near the distal tip portion 50 so thatrotation of the steering knob 70 causes deflection and bending of theshaft 20 near the distal portion 50 as shown.

The operative distal tip portion 50 may take any known construction inthe art. For example, but not by way of limitation, the operative distaltip portion 50 may include an implantable and detachable occlusiondevice, a probe assembly, an expandable basket assembly, an expandableballoon or body, one or more electrodes for sensing, pacing, and/orablating, one or more markers for identifying the distal tip portion, animaging device, and any combination of the above. In the embodiment ofthe operative distal tip portion shown, two ring electrodes 100, 110 aredisposed along the length of the distal tip portion 50 to provide radiofrequency energy for ablation and/or sensing of electrical activity inbody tissue. In addition, a radiopaque marker band 120 is secured to thedistal tip portion 50 to facilitate visualization of the distal tipportion 50 inside the body using fluoroscopy.

FIGS. 2A and 2B relate to illustrate the body or shaft 20 of FIG. 1 inmore detail. The shaft 20 includes a proximal shaft portion 140, andintermediate shaft portion 145, and a distal shaft portion 150. Theshaft increases in flexibility from the proximal shaft portion 140 tothe distal shaft portion 150. The distal shaft portion 150 includes thedistal tip portion 50 and is comprised of a ribbon braid 170 ofcounter-wound double Nitinol wires embedded in a layer of hydrophobicpolymer 180 to prevent the braiding 170 from being exposed. The polymerlayer 180 may be covered with a hydrophilic coating. This constructionallows the distal shaft portion 150 to be flexible or bendable in alateral direction to facilitate steering of the shaft 20, but has enoughtorsional strength to allow torque to be efficiently transmitted by theuser from the handle to the distal shaft portion 150 without give in theshaft 150.

The ribbon braid 170 is preferably made from Nitinol in order to createa shaft that minimizes kinking, transmits a high amount of torque, andretains its shape after being bent. Importantly, a Nitinol braid 170allows increased flexibility in the distal tip portion 50, but keeps theinterior lumen from collapsing by inhibiting kinking. Additionally,because Nitinol is a memory metal, a user may easily maintain the distaltip portion 50 in a desired shaped throughout a surgical procedure. Inother embodiments, the braid 170 may be made of different materials suchas metal alloys (e.g., stainless steel, carbon fiber).

The proximal shaft portion 140 and intermediate shaft portion 145 arepreferably made of a substantially hollow Nitinol tubing 182 coated withthe hydrophobic polymer layer 180. The polymer layer 180 may be coveredwith a hydrophilic coating. The Nitinol tubing 182 is designed totransmit torque to provide a substantially one-to-one correspondencebetween rotation of the proximal shaft portion 140 and distal shaftportion 150. The Nitinol tube 182 provides the shaft 150 with sufficientflexibility for advancing the shaft 150 through a tortuous lumen pathand sufficient torsional strength to efficiently transmit torque fromthe handle 60 to the distal shaft 150. The tube 182 is also preferablymade of Nitinol to minimize kinking and because Nitinol is a memorymetal that retains its shape after being bent. In other embodiments, thetube 182 may be a made of a material other than Nitinol such as, but notby way of limitation, carbon fiber or a metal alloy such as stainlesssteel.

The shaft 20 increases in flexibility from a proximal junction 184,where the shaft 20 meets a luer attachment 185, to a distal junction186, where the Nitinol tube 182 attaches to the Nitinol braid 170 of thedistal shaft portion 150. This increase in flexibility is created bymaking a plurality of slits or cuts 188 along the hollow tube 182. Theseslits 188 extend perpendicular to a longitudinal axis of the shaft 20.An increase in flexibility in the shaft 20 from the proximal junction184 to the distal junction 186 may be achieved by increasing the depthof the slits 188 as one progresses from the proximal junction 184 to thedistal junction 186 and/or by increasing the number of slits 188 perunit length of tube 182 as one progresses from the proximal junction 184to the distal junction 186. As best seen in FIG. 2A, the number of slits188 per length of tube increases gradually from the proximal shaftportion 140 to the distal junction 186. Additionally, the slits 188become increasingly deeper toward the distal junction 186. As a result,a transition in stiffness is formed, whereby the shaft 20 becomesprogressively more flexible from proximal shaft portion 140 to distalshaft portion 150. The number of slits 188, location of slits 188,frequency of slits 188, orientation of the slits 188, size of the slits188, and/or depth of the slits 188 may be varied to vary the transitionof stiffness according to the desired application of the shaft 20.

While preferred embodiments and methods have been shown and described,it will be apparent to one of ordinary skill in the art that numerousalterations may be made without departing from the spirit or scope ofthe invention. Therefore, the invention is not limited except inaccordance with the following claims.

What is claimed:
 1. A medical device shaft for connection with a handleand for insertion within a body, comprising: an elongated, deflectableshaft having a proximal shaft portion, an intermediate shaft portion,and a distal shaft portion, the elongated, deflectable shaft having atransition in stiffness from the proximal shaft portion to the distalshaft portion; wherein the elongated, deflectable shaft includes alongitudinal axis and a plurality of slits that extend perpendicular tothe longitudinal axis of the deflectable shaft, wherein at least one ofthe number of slits, the location of slits, the frequency of slits, theorientation of the slits, the size of the slits and the depth of theslits are varied to vary the transition of stiffness in the shaft. 2.The medical device shaft of claim 1, wherein the shaft decreases instiffness from the proximal shaft portion to the distal shaft portion.3. The medical device shaft of claim 1, wherein the shaft includes agreater number of slits near the distal shaft portion than near theproximal shaft portion.
 4. The medical device shaft of claim 1, whereinthe number of slits per unit length is greater near the distal shaftportion than near the proximal shaft portion.
 5. The medical deviceshaft of claim 1, wherein the slits on the shaft have a depth and slitson the shaft near the distal shaft portion are deeper than the slits onthe shaft near the proximal shaft portion.
 6. The medical device shaftof claim 5, wherein the depth of the slits increases gradually from apoint on the shaft near the proximal shaft portion to a point on theshaft near the distal shaft portion.
 7. The medical device shaft ofclaim 1, wherein the distal shaft portion does not include slits.
 8. Themedical device shaft of claim 1, wherein the distal shaft portionincludes an interior ribbon braid that provides torqueability,bendability, and prevents the distal shaft portion from collapsing. 9.The medical device shaft of claim 8, wherein the ribbon braid isembedded in a layer of hydrophobic polymer.
 10. The medical device shaftof claim 9, further including a hydrophilic polymer layer over thehydrophobic polymer layer.
 11. The medical device shaft of claim 9,wherein the ribbon braid includes counter-wound double wires made from ametal alloy.
 12. The medical device shaft of claim 11, wherein the metalalloy is Nitinol.
 13. The medical device shaft of claim 1, wherein thedeflectable shaft includes a high torsion, bendable tubing.
 14. Themedical device shaft of claim 13, wherein the tubing is Nitinol tubing.15. The medical device shaft of claim 13, further including ahydrophobic polymer layer on the Nitinol tubing.
 16. The medical deviceshaft of claim 15, further including a hydrophilic polymer layer on thehydrophobic polymer layer.
 17. A medical device shaft for connectionwith a handle and for insertion within a body, comprising: an elongated,deflectable shaft having a proximal shaft portion, an intermediate shaftportion, and a distal shaft portion, the elongated, deflectable shafthaving a transition in stiffness from the proximal shaft portion to thedistal shaft portion; wherein the elongated, deflectable shaft includesa longitudinal axis and a plurality of slits that extend perpendicularto the longitudinal axis of the deflectable shaft, wherein the shaftincludes a greater number of slits near the distal shaft portion thannear the proximal shaft portion.
 18. A medical device shaft forconnection with a handle and for insertion within a body, comprising: anelongated, deflectable shaft having a proximal shaft portion, anintermediate shaft portion, and a distal shaft portion, the elongated,deflectable shaft having a transition in stiffness from the proximalshaft portion to the distal shaft portion; wherein the elongated,deflectable shaft includes a longitudinal axis and a plurality of slitsthat extend perpendicular to the longitudinal axis of the deflectableshaft, and wherein the number of slits per unit length is greater nearthe distal shaft portion than near the proximal shaft portion.
 19. Amedical device shaft for connection with a handle and for insertionwithin a body, comprising: an elongated, deflectable shaft having aproximal shaft portion, an intermediate shaft portion, and a distalshaft portion, the elongated, deflectable shaft having a transition instiffness from the proximal shaft portion to the distal shaft portion;wherein the elongated, deflectable shaft includes a longitudinal axisand a plurality of slits that extend perpendicular to the longitudinalaxis of the deflectable shaft, and wherein the slits on the shaft have adepth and slits on the shaft near the distal shaft portion are deeperthan the slits on the shaft near the proximal shaft portion.
 20. Amedical device shaft for connection with a handle and for insertionwithin a body, comprising: an elongated, deflectable shaft having aproximal shaft portion, an intermediate shaft portion, and a distalshaft portion, the elongated, deflectable shaft having a transition instiffness from the proximal shaft portion to the distal shaft portion;wherein the elongated, deflectable shaft includes a longitudinal axisand a plurality of slits that extend perpendicular to the longitudinalaxis of the deflectable shaft, and wherein the depth of the slitsincreases gradually from a point on the shaft near the proximal shaftportion to a point on the shaft near the distal shaft portion.